1. Field of the Invention
The present invention relates to impact tools and methods, and in particular, to compact devices that fit over a nut, bolt head or other fastener for turning them.
2. Description of Related Art
Threaded fasteners such as nuts and bolts may be tightened and left in place for long periods of time. Loosening such fasteners may be difficult because of various effects such as rusting, debris on threads, deformation of the fastener, chemical corrosion and bonding, etc. in many situations the ability to loosen the fastener may be critical for maintaining an associated machine. For example, an automobile engine has many replaceable parts that periodically wear and must be replaced by loosening bolts and nuts or other fasteners.
Applying torque to a fastener with a wrench having a long lever arm may exacerbate the problem by snapping a threaded shank or by rounding or shearing a bolt head. After such a catastrophic failure a mechanic will probably need to drill out the fastener, a difficult and time-consuming procedure.
Penetrating liquids are sometimes used to help loosen the frozen fastener but a penetrant may be ineffective in some situations, e.g. with deformed fasteners.
In some circumstances the fastener can be loosen by mechanical or thermal shock. For example, the fastener can be heated with a simple torch which causes a differential thermal expansion that can loosen the fastener. Alternatively, hitting the fastener with a hammer may break a bond that prevents loosening. However, a hammer blow will often produce an ineffective axial shock wave without applying a loosening torque.
Known bolt/nut removers employ a socket-like device with internal flutes that can grip a rounded bolt head. A wrench may be applied to this device to remove the bolt. A known impact driver has a body with an internal cam mechanism for driving a distal shaft that is fitted with a socket or other accessory. The driver body may be struck with a hammer, which causes the cam to rotate the shaft and its accessory.
See also U.S. Pat. Nos. 3,366,187; 3,799,011; 3,861,250; 4,708,209; 4,807,349; 4,864,902; 5,904,076; 6,370,993; 6,668,686; 7,044,035; and 7,089,833.
Accordingly, there is a need for an improved impact device that can simply and efficiently turn a fastener.